Reduce vibration: Aquadrive vs Flexible Coupling

[Boater On Thames]

I am thinking to add an Aquadrive or Flexible Coupling to the shat to try to reduce some vibration. Will this help? Which one will have a better result? Any advice? Thanks.

My boat has some vibration that mostly happens at a low engine speed around 550-650PRM both at ideal or driving. The vibration will go once the engine speed is over 750-800PRM. The problem is that my boat is on the River Thames, I have to drive slower than 750PRM most of the time to avoid speeding. So I am trying to find a solution to reduce the low-speed vibration. Thanks.

 

[penfold]

Aquadrive and similar dual constant velocity joint systems insulate vibration very well, they will do exactly what you want and pretty much eliminate low speed vibration.

 

[Elessar]

I am thinking to add an Aquadrive or Flexible Coupling to the shat to try to reduce some vibration. Will this help? Which one will have a better result? Any advice? Thanks.

My boat has some vibration that mostly happens at a low engine speed around 550-650PRM both at ideal or driving. The vibration will go once the engine speed is over 750-800PRM. The problem is that my boat is on the River Thames, I have to drive slower than 750PRM most of the time to avoid speeding. So I am trying to find a solution to reduce the low-speed vibration. Thanks.

Have you had your prop(S) balanced? Got rid of the vibration on mine.

 

[Croftie]

Has the vibration always been there or has it only developed since you had all the trouble removing/replacing the couplings and trying to remove the cutlass bearings but didn't manage to do earlier in the year. Is it happening on both or only one engine?

 

[Boater On Thames]

@Elessar . The Props are balanced and refurbished during August.

@Croftie . That little vibration has always been there even when I first view her three years ago. That happening in both sizes. If only driving one size, the vibration is less, then it will increase when driving both engines. Just I previously thought the little vibration at low speed is normal and acceptable. I am now thinking to do more improvement on her during winter and next lift. So I think it may be worth adding a little thing to make her better.

 

[kashurst]

If the vibration is just at low rpms, you could try changing the engine mounts at the gearbox end. Easier than fitting aqua drives etc.

 

[Boater On Thames]

Good idea. Maybe I should find 4 anti-vibration engine mounts to have a try. Any suggestions where to buy?

 

[Mr Googler]

Good idea. Maybe I should find 4 anti-vibration engine mounts to have a try. Any suggestions where to buy?

Robush……Cushyfloat - Robush Ltd

61a oe was cushyfloat. They knew the right ones when I told them the engine make/ model

 

[Boater On Thames]

@Mr Googler . So, you installed these Robush mounts to your engine? How is the result? Thanks.

 

[Mr Googler]

@Mr Googler . So, you installed these Robush mounts to your engine? How is the result? Thanks.

mine where shot at the gearbox end and put the engine out of alignment (shaft hard to turn by hand). Can’t say I noticed Any difference after apart from the shaft turned by hand once changed and lined up again.

 

[Boater On Thames]

Ok. This is different from mine. My shaft can easily turn with one hand.